External rearview mirrors are often utilized in heavy trucking both to reflect the traffic to the rear of the vehicle and to show the driver the condition of the load being carried. Rain, mud or snow splattered across a mirror surface drastically reduces its effectiveness. It has therefore become desirable to obtain some form of mirror wiper arrangement.
The above problem has been realized to limited degree in view of the below listed references.
U.S. Pat. No. 3,968,537 to Wagenhofer discloses a detachable wiper that is mountable to the top of an existing rearview mirror frame. The wiper arrangement uses clamps to secure the wiper drive and wiper blade to the mirror frame. The device drives a wiper blade from the frame top across the surface of the mirror. An electric motor is provided for driving the wiper blade which is cantilevered from the drive mechanism atop the mirror frame. The device must be mounted to mirrors of particular configurations since there does not appear to be provision for adjustments in the mounting mechanism for mirrors of differing configurations. Furthermore, it does not appear there are adjustment capabilities for evenly biasing the full length of the wiper blade along the mirror surface.
U.S. Pat. No. 4,037,286 to Medearis discloses a wiper for rearview mirrors that is very similar to the Wagenhofer arrangement. Medearis, however, incorporates the mirror as an integral part of the entire assembly with heating elements enclosed within the mirror compartment to avoid frost buildup. Medearis discloses a wiper blade that moves vertically along the length of the mirror. The blade is moved through a crank arm arrangement and electric motor that is substantially similar to the Wagenhofer arrangement.
U.S. Pat. No. 4,212,091 to Jones discloses a wiper apparatus for rearview mirrors wherein the wiper is reciprocated across the surface of the mirror by a pair of cylinders. The cylinders are mounted within the body of the mirror frame. The two cylinders are vertically offset from one another and include piston shafts joined in a common upright bar member that reciprocates in response to extension and retraction of the cylinders. A wiper blade carrier assembly is also mounted to the rod for engagement with the mirror surface. No selective adjustments are disclosed since the mirror and wiper assembly are disclosed as a single operational unit. Another rearview mirror and wiper assembly combination is disclosed in U.S. Pat. No. 3,866,258 to DeGraw. Like the Jones reference, DeGraw makes use of a pair of cylinders for extension and retraction to move a wiper blade carriage over an external mirror surface. Springs are provided to return the carriage to a retracted, starting condition following extension of the cylinders.
Another form of integrated wiper and mirror arrangement is shown in U.S. Pat. No. 4,339,169 to Addison. This arrangement makes use of a crank mechanism for effecting wiping motion of a blade across the adjacent mirror surface.
Another integral mirror-wiper combination is disclosed in U.S. Pat. No. 3,685,087 to Pittman. The Pittman mechanism makes use of a motor and chain drive mechanism connected to a wiper carriage for moving the wiper carriage vertically over a mirror surface. A spring mechanism is utilized for adjustably biasing the blade against the mirror surface. The connection between the wiper blade carriage and the wiper blade is situated at the approximate center of the wiper blade frame. The complex drive mechanism and mounting arrangements require the assembly to include the mirror and mirror frame.
U.S. Pat. Nos. 4,306,328 to Layton and No. 4,307,482 to Palmer both disclose other forms of mirror wiping arrangements.
Of the above references, most are relatively complex and, hence, increase the overall cost for the rearview mirror. This is undesirable since the mirrors are typically situated in a relatively hazardous position alongside the vehicle, are subject to damage and require fairly frequent replacement. Replacement costs may be minimized by providing a wiper assembly that is mountable to an existing, commercially available rearview mirror. However, there are several forms of mirrors currently available on the market, and it is does not appear that any of the above referenced wiper attachments would readily adapt to more than one of the commercially available mirrors.
The present invention represents a solution to this problem by providing a wiper attachment that will readily mount to a variety of conventional standard mirror configurations. The present mount and wiper assembly also represents a substantial operational improvement due to its simplicity of construction. For example, the present attachment requires only a single cylinder to drive the wiper carriage across the mirror surface. By using a single cylinder, cost is substantially reduced (over the two-cylinder models), and maintenance is consequently significantly reduced. Operation is another consideration. It is advantageous to use a single cylinder driving a wiper frame since two cylinders connected to the same wiper carriage may bind against one another should their strokes be unequal.
The present wiper attachment may be easily and quickly attached to existing forms of rearview mirror frames without requiring special tools or expertise. Further in this regard, the present wiper attachment mounts to existing mirrors in such a manner that the attachment may not be easily removed from the mirror frame to thereby guard against theft.